Process for refining raw carbon disulphide



oct, 29,'"19211 P. SIEDLER El AL PROCESS FOR REFINING RAW vCARBON DISULPHIDE kFila o t. 11. 1926 denser Crue/e Qaror) fsu/fluide- Patented Oct. 29, V1929 UNITED STATES PATENT OFFICE PHILIPP S`IEDLER, OF GBIESHEIM-ON-THE-MAIN, AND EUGEN SCHULTE, 0F SCHWAN- HEIM-ON-THE-MAIN, GERMANY, .ASSIGNORS T0 THE FIRM I. G. FARBENINDUSTBIE, AKTIENGESELLSCHAFT, OF FRANKFORT-ON-THE-MAIN, GERMANY PROCESS FOR ABEFININ'G RAW CARBON DI'SULPHIDE Application illed October 11, 1920, Serial No.

This invention relates to the refining of the raw carbon disulphide obtained by the usual processes. Hitherto such rening was preferably elfectcd either by rchemical means or by fractional distillation from a boiler or the like apparatus, or by both means. Recently it has been attempted to accomplish a continuous treatment by'means of rectifyingcolumns in combination with other `Vphysical or chemical refining methods. Hereby one has, it is true, succeeded in removing the main quantity of sulphuretted hydrogen and other `volatile contaminations, and, at the same time, recovering the sulphur co iously contained in the raw product and a so the non-volatile sulphurous compounds which might be present; however this result could only be attained by withdrawing, from the boiler, a highly concentrated carbon disulphide solution of these substances, Without accomplishing the separation up to the obtainment of molten sulphur, which could immediately be reused in the further production of carbon disulphide. This aim has, owing t0 the diilculty in reachin it, not yet .been attained. Thisis, as we gave recognized, due to the fact that-carbon disulphide, even if not preserved under water, is generally saturated to a greater or less extent with water. At temperatures of about 100 C. or more re` quired for obtaining molten sulphur, dissolved or molten sulphur already reacts to a certain extent with Water, forming sulphuretted hydrogen, by which the carbon disulphide to be subjected to distillation is again permanently contaminated."

By our present invention we have succeeded -in overcoming this difficulty. This invention is carried out as follows :-For rending the raw carbon disulphide merely according to the principles of rectilication, two columns are used in such a manner that in the rst column (A) only a previously purified carbon disulphide as distillate is contemplated, whereas in the second column (B) from the previously refined product quite pure carbon disulphide as ldistillate, and simultaneously only a little carbon disulphide containing sulphur as a boiling liquid in the boiler isjobtained which liquid is then 141,020, and in Germany October 24, 1925.

transferred to the boiler of the column A. As the boiling-pomt of this solution approximates that of pure carbon disulphide, and at this temperature sulphur does not yet react with the traces of water always present, the carbon disulphide distilling o from B can no more be contaminated by sulphuretted hydrogen.

For carrying out this process it is further important that the carbon disulphide vapors distilling oil from the columns are withdrawn in the proximity of the bottom ends of the columns and thence are again conveyed to the top for further treatment, i. e. from A to the top of B, and from B to an elevated device for condensing the pure final product. The connecting conduit-pipes form communicating vessels with the corresponding columns, in which vessels the carbon disulphide vapors must be approximately equilibrated if'during the distillation currents possibly detrimental to the rectifying action are to be prevented.

A further important requirement is that the gases escaping'froni the two reflux-condensers above the columns A and B, substantially consisting of sulphuretted hydrogen and other volatile sulphur-ous compounds, besides a little carbon disulphide, are jointly conveyed to a` low-temperature condenser arranged above the reflux-'condenser from which low-temperature condenser on the one hand, the remaining part ot' the carbon disulphde here condensed Ais conveyed to column A, and, on the other hand, the Waste gases are conducted away for further use.

In its continuous course the rectification takes place in the manner hereafter described reference beinghad to the single figure o the annexed drawing' in which a refining plant for carrying out our present invention is diagrammatically illustrated. The column A is irrigated with carbon disulphide, The warm gases entering from below expel the sulphuretted hydrogen and other easily volatile parts to the reflux-condenser A1 by which the main part of the carbon disulphide carried along with them is separated from the gases and flows back to A. The last parts of carbon disulphide contained in the sulor intermittently liquid sulphur showing, on

an average, a purity of about 98 per cent may be withdrawn from the still. The vapors entering at B from X are, for the most part, condensed by B2; the remaining part of sulphuretted hydrogen passes to D through B2. During its passage through B, the boilingpoint of pure carbon disulphide it attained 1n the proximity of the lower end of the column; the quite pure carbon disulphide vapors are here conducted up to the condenser C through pipe Y. In this way a carbon disulphide solution the boiling-point of which surpasses that ol' the pure product only by a few degrees and containing a small percentage of sulphur arrivesat the boiler B2. This solution is continuously or intermittently used with others to feed A2 through pipe e. Preferably the' still B2 is placed above A2 and constructed to fgr an annular space around the bottom end o For heating the boilers A2 and B2 any known device may be employed. Preferably .the columns and boilers are surrounded by a jacket E to form a unity which'may be insulated outwardly by a. suitable bad conductor of heat.

According to our improved process we thus obtain continuously and in a merely physical wayz--Purest carbon disul'phide with practically quantitative output, sulphuretted hydrogen in combination with other volatile by-products in a highly concentrated form;

sulphur together with non-volatile contaminations in the form of a molten mass which may be immediately reused for the production of carbon disulphide.

1. Process of refining raw carbon disulphide, comprising irrigatingwith raw carbon .`disulpl1ide a first column provided with a reflux-condenser, the boiler of which is kept at temperatures above 120 C., and irrigating with the previously puriled carbon disulphide supplied -from the said column, a similar second column the boiler ot' which is kept at a tem erature somewhat above the boiling point o pure carbon disulphide.

2. In the process of refining raw carbon dxsulphide .according to claim' 1, further Jointly cooling the waste gases escaping from and using the carbon disulphide thus obtained for again irrigating the first column.

3. Process of refining raw carbon disulphide, comprising irrigating with raw carbon disulphide a first column provided with a reflux-condenser, the boiler of which is kept at.

temperatures above 120 C., irrigating with the previously purified carbon disulphide supplied from the said column a similar second column the boiler of which is kept at a temperature somewhat above the boilingpoint of pure-carbon disulphide, withdrawlng the carbon disulphide vapors from the first and second columns in the proximity of their lower ends, and conducting the vapors at least up to the level of the upper end of the columns before allowing them to condense. In testimony whereof we aflix our signatures. l

PHILIPP SIEDLER.

EUGEN SCHULTE.

the relux-condensers ot' both the columns 

